Natural gas as it exists in the form when taken from a mine, an oil field, or a gas field typically contains heavy hydrocarbon components and other impurities in addition to the predominant component of methane. The heavy hydrocarbon impurities, i.e., for present purposes any hydrocarbon having an organic structural formula of two or more carbon atoms and typically having carbon atoms in the range of C.sub.2 -C.sub.10, are notably present when the natural gas is taken from an oil field. Before the natural gas can be used efficiently as a feedstock either as a fuel or as a chemical feed, it is purified by removing the higher order hydrocarbon components than methane and other impurities. The purification process may embody a cryogenic distillation of the natural gas using known refrigeration techniques such that a liquefied and purified natural gas feedstock is provided.